How do I loosen a cleat bolt that’s got a rounded hex head? I’ve had the cleats fitted for longer than I care to remember and a couple of the bolts have become pretty seized up. Unfortunately, while attempting to loosen one of them I’ve rounded off the hex head. Now I can’t loosen it at all. I’ve tried a new hex key but to no avail.
Any tips or advice on how to loosen a cleat with a rounded 3mm hex head?
You could go to your nearest hardware / fastener shop and buy an easy out [screw extractor] bit, commonly used for this purpose. Just be extremely careful while drilling in the shoe, especially with respect to hand position, and ensuring the shoe is secured in its place so you can have two hands on the drill and none on the shoe.
If you’re replacing the cleat you can take a dremel and make a straight line cut in the bolt and remove with a flat head screwdriver. This will only work if you plan on replacing the cleat though…
Edit: Here’s a link to better explain the concept: Removing a Stripped Screw with a Dremel - YouTube
I’ve had this happen previously and removed them by cutting a slot into the screw head and used a large flat blade screwdriver to remove it. I used a Dremel with a cut off wheel to cut the slot.
EDIT: nipped at the line by @SamMose
Before you do any of those, try carefully placing your driver and then tapping it a few times with a hammer. Sometimes, this gives you the purchase you need on the screw.
Updated to add: make sure you are using a straight-sided wrench (not a ball-end wrench).
Always do this, especially on mtb shoes
I’ve drilled out the top of the bolt and then used pliers to grab the stub. On my time atacs it happens quite often
You could TIG weld a 4mm allen to the head of the bolt and get it out that way.
If you are using “eazy out’s” try to find ones that have left hand drill bits, offen will remove stuck fasner with drill bit.
If it’s seizing due to rust, some WD40 might help. Just be sure to clean it out well before replacing and don’t forget grease when putting a new one in. The grease will hopefully stop this from happening next time =)
If they’re road shoes you can cut as much of the cleat away as possible to be able to get purchase on the side of the head w/ channel locks, try to get some wd40/solvent in, let it soak and remove w/ the channel locks.
Cutting the cleat away is a pain. I think I used a tiny hand saw (carefully) that I happened to have.
Sometimes using a torx will get a rounded out Allen if it’s not too far gone.
I have successfully drilled out the centre and they come out easily. Especially if they are rusted in.
If you can get any purchase on the flange of the screw, vise grips may work.
Not to help get it out but grease on the cleat bolt threads helps prevent this
Thanks everyone. I’ve just ordered a Dremel. I’ve always fancied one of these - now I have the perfect excuse! Cheers.
KEO cleats always come with New Screws… so if they ever get stuck… Dremel… you name it… destroy the screw… who cares… was going into the Parts Bin otherwise… just in case KEO Cleats stop coming with New Screws… which… more than likely will only happen if they replace the KEO Cleats with something Newer… after all… they had Delta before then… which also came with New Screws… which are Exactly the Same! 
Look KEO for a reason!
Update: the dremel did the job. I cut a slot in the head and my screwdriver (and some wd40) did the rest. Thanks guys.